GreenDieselEngineering wrote: The cold weather does have a significant effect on fuel economy and is a combination of several parameters. Transmission has a warm-up cycle based on fliud temp and it usually lasts between 2-10 minutes depending on load/drive cycle. During this time it tends to hold a lower gear to increase rpm and warm up the trans fluid faster, at a certain temp the shift strategy reverts to normal mode. This also holds true for the engine warm-up, uses more fuel to increase heat output, two pilot injection events and longer combustion heat release aid in transferring more heat to the head and block. The warm-up cycle is off when coolant temps reach the 140's.

The short trips with intervals of 3+ hours will have a negative impact on fuel economy. The severity increases with the length of soak, lower ambient temps, snow, 4x4, etc.

Low coolant temps (160-176 F) in the winter are not directionally good and a 195 F thermostat would provide significant benefit. Increased oil temps and liner temps will help make the combustion more efficient and further reduce HC emissions, all leading to better fuel economy.

The CRD is best suited for longer periods of highway driving and this becomes more evident during the winter months. City driving has no TC lock-up in the trans and the repeated warm-ups are just not helping. Blocking part of the radiator fresh air flow should help somewhat, but we have not tested it to validate the impact.

The confidence behind the wheel during snowy winter driving is still the primary motivator for the KJ, especially the ESP on the 2006 models. We tend to get to throttle happy and the ESP keeps everything in line. Our 2005 with turbo kit is for the fun factor...however, without snow tires it is mainly used on clear roads.

Thanks for the feedback.
GDE

Thanks. If it's normal then I'm fine with that. Just didn't know what normal was for this vehicle.

flman wrote:Make sure the card board is not blocking air flow to the CAC?

It's three sections of black painted (so you can't see it's there unless you look real close) cardboard that slip in behind the grill when the hood is opened. They do block most of the CAC. The bottom air inlet under the bumper is still all open. Don't all the winter covers block most of the CAC on diesel trucks? My Ram and YJ Cummins also get the black cardboard in the winters unless they're towing. The TDI has never been cardboarded.

If they cover the outer grill not really, but directly in front of the CAC, yeah. But I doubt it is gonna hurt anything, I know my Cummins book said not to cover it 100%, if you notice alot of trucks have a small opening in the grill cover. But like you said, you are getting air through the bumper.

I got to figuring up my tanks lately in my spreadsheet and after I accounted for the 1 MPH too fast that my speedo was on stock tires, and the 1 MPH too slow that it is now, the results were that post-tune I am now getting 0.0-0.5 MPG more than I was before. I think that this tank of fresh diesel from the truck stop will get me up a little higher still. I also did not add any anti-gel to this tank. I think that the tune may get back the mileage I lost with the AT tires which is a pretty good deal. For what it's worth, my EVIC was 2.0 MPG high at the end of the tank so it's not off as bad as some users have experienced.

For the first tank that is acceptable. Need to keep in mind you purchased the "HOT" tune and you mentioned that the TC shudders very bad. When the TC shudders, you are not driving conservatively, so the fuel economy with suffer even though you are driving "conservatively". The fuel economy should improve over the next couple of tanks as you adjust to the tune. Our BFG all-terrain tires cost us 3 mpg, but the improvement in grip seems worth it. We adjusted the EVIC calculation with the tune to bring it a little closer to reality, there are just too many contributers to fuel economy that the EVIC will never be very good considering in the software it can only be adjusted with a 2-point linearization.

I see a much better correlation from EVIC to hand calculated with your newest adjustment that came in my recent Hot Tune upgrade as compared to the older version of the Eco tune. Nice job.

Interestingly it seems the colder it gets the higher % optimistic the EVIC becomes as compared to hand calculated. I'd be interested to hear if anyone else sees that correlation or if it's just me.

Just curious on your thoughts about something. I am using an Elephant hose mod. Considering how much blow-by occurs with this engine is there an advantage to having those oil vapors going back into the intake in terms of power/economy/longevity/warm up? I'm thinking the amount of vapor is trivially small but just thought I'd ask . . .

Dave wrote:I have been considering an elephant hose because I don't want all the snot (that my previous homemade crankcase vent collected) in my CAC. Do you get a mess on your garage floor?

The only time I noticed some drips was this Fall after towing my trailer. Otherwise it doesn't seem to be a noticeable amount. Although I don't keep my garage floors pristine so it might just blend in with the other stains, dirt, dust, etc. . .

Just curious on your thoughts about something. I am using an Elephant hose mod. Considering how much blow-by occurs with this engine is there an advantage to having those oil vapors going back into the intake in terms of power/economy/longevity/warm up? I'm thinking the amount of vapor is trivially small but just thought I'd ask . . .

With the small amount of oil going through the system it will not have a significant effect on power/economy/longevity or warmup. We drained our CAC at 70,000miles and were only able to get a couple ounces out, most of it stays airborne and goes through the engine. Eliminating the soot is the best way to prevent gunk build-up and a set of Samcos with silicon lining to stop oil bleed through of the hoses.

I have not had any issues with the Provent icing, although I live in a warm area (southern California) I do get to cold places occasionally. I had the EHM and wife didn't like the smoke, it never dripped too much and the Provent can make a mess if not cleaned carefully, but I still recommend one. Disconnecting the EGR whether b the GDE system, the SEGR or just pulling the MAF plug ( but CEL light stays on) all reduce the EGR gases contaminating the intake process, do at least one of them. Strongly agree with GDE that there is a fuel cost to BFG AT/KO tires but they are terrific tires, used them for a 1,000 mile unpaved road trip, other off road activities and some snow action too--and they still ride OK on regular pavement, well worth the fuel penalty if you do serious snow, off road or tow.

Ã¢â‚¬Å“There are only two ways to live your life. One is as though nothing is a miracle. The
other is as though everything is a miracle.Ã¢â‚¬Â - Albert Einstein

Looking back at mileage logs for other vehicles IÃ¢â‚¬â„¢ve commuted with shows a similar % drop in mpgÃ¢â‚¬â„¢s (once I replaced the ATR tires) compared to summer. However the magnitude of this drop seems larger than I can account for in terms of fuel BTUÃ¢â‚¬â„¢s and engine/transmission warm-up times. But it appears now that thereÃ¢â‚¬â„¢s an important variable I wasnÃ¢â‚¬â„¢t considering before: Prevailing wind directions.

I live northwest of my job. In the winter months the wind in Iowa is on average from the Northwest and its average speed is the highest in the months of Dec, Jan and Feb. I drive to work around 6-6:30am when wind speeds are at their lowest average speed for a given day. My return drive home is in the afternoon when the wind speeds are their highest average speed for a given day. These months are also the coldest so the air density is at its highest so will have a bigger impact on wind drag than in the summer. Sooooooo, my morning commute is typically with the wind but the wind is typically weak. My return trip is typically into the wind when itÃ¢â‚¬â„¢s typically at its strongest. Not the best combination for maximizing fuel economy.

When I first got my HOT tune, I (of course) played around with it just a little bit to see if the shudder would be there. And it was bad, as I noted. But I do not drive that way normally. My normal driving style now is VERY conservative. So conservative that people behind me get upset leaving from red lights and slowing down to red lights. I stay inside the speed limit. I don't idle for extended periods. Like I said, I've been doing real world study in the fuel economy area for a few years trying to learn what really helps and hurts in the real world and obviously driving style is the main contributor.

I'm currently running a "fresh" tank of Flying J truckstop diesel...and I've been slightly more highway than city on this tank up to this point...and my economy is even lower right now than it was with the Walmart diesel I had been using. Interesting...

I agree the AT tires don't help economy. But the grip in Winter weather is well worth the tradeoff. On my previous CRD...I lost 2 MPG with these same tires. I'm assuming the loss will the the same with this CRD. The weather has been colder and snowier than usual this year in Kentucky also. I'm really hoping to start seeing mid-20 MPG figures once the weather breaks finally.

I my area Flying J uses Marathon and blend #1 heavily. I prefer Sunoco and always opt for the premium (additional 2 or 3 cents). I also like Torco and Shell. Next on my list is Citgo and Crystal Flash although I get mixed results. I can't speak for your area, but the point is; I find it worth experimenting.

On my previous CRD that was 100% bone stock drivetrain except muffler...I NEVER saw mileage readings this low. I remember one tank of 19 MPG and that was it in the year that I had it. Otherwise I was always around 23-24 MPG with the same lift and same tires I have now.